This invention relates to a corrugated pipe with a joint at the end, and a method of forming the joint on an end of the corrugated pipe. The term "corrugated pipe" as used herein is intended to mean both a spirally corrugated pipe--the parallel, alternate ridges and grooves of the wall are spiral, and an annularly corrugated pipe--the parallel, alternate ridges and grooves of the wall are annular.
An injection molding method is well known in the art in which a liquid-phase monomer, such as a norbornene (phonetic) type monomer, which is quickly polymerized and solidified at room temperature (without heating it) is injected into metal molds at a high temperature, for instance about 90.degree. C., under a high pressure, for instance about 3 to 40 kg/cm.sup.2, to form a variety of moldings (cf. Japanese Patent Application (OPI) No. 112126/1988 (the term "OPI" as used herein means an "unexamined published application").
On the other hand, a variety of pipe joints are available which are formed in addition to pipes.
It is not always simple to mold a pipe joint for a large diameter corrugated pipe, for instance 1000 mm to 2000 mm in inside diameter, by the above-described injection molding method, because the metal mold is necessarily bulky and the molding may suffer from settling or shrinkage. Furthermore, practicing the injection molding method is accompanied by high temperature and high pressure, and needs a pressure maintaining process after injection molding as is disclosed by the aforementioned Japanese Patent Application. Thus, the method suffers from a problem that the attached facilities are intricate in addition to the problem that the molding machine is bulky. Furthermore, because of the pressure maintaining process, it is impossible to increase the molding efficiency.
On the other hand, in the case where the reinforcing rib of a large diameter pipe buried in the ground is spiral, it is considerably difficult to screw the end portion of the large diameter pipe into a large joint formed as one separate component.